Ground engaging hay bale rolling apparatus

ABSTRACT

A hay bale rolling apparatus adapted to be drawn along a swath or a windrow of hay behind a tractor to roll the windrow into a series of separate bales in contact with the ground. The apparatus is entirely hydraulically operated from a tractor hydraulic system and has a single two-position mechanical control valve to control a cycle of baling, bale release and return to baling. The valve may be actuated to release a bale manually by an operator on a tractor or automatically by a sensing means which directly senses the diameter of a bale; and is automatically returned from release position to baling position after a bale is released.

United States Patent [1 1 Gay et al.

1451 Aug. 14, 1973 GROUND ENGAGING HAY BALE ROLLING APPARATUS PrimaryExaminer-Russell R. Kinsey [75] Inventors: James E. Gay; John W. Bliss,both of fi g g Wagner Allen Stenman &

Vinton, Iowa 6 or [73] Assignee: Starline, Inc., Harvard, Ill. [57]ABSTRACT [22] Filed; June 17, 1971 A hay bale rolling apparatus adaptedto be drawn along a swath or a windrow of hay behind a tractor to rollthe [21] App! windrow into a series of separate bales in contact withthe ground. The apparatus is entirely hydraulically 0p- 52 US. Cl56/16.4, 56/1, 56/341 erated from a tractor hydraulic system and has asingle [51] Int. Cl AOld 75/00 -p mechanical Control Valve Comm] a [58]Field of Search 56/1, 341, 342, 343, cycle of baling, bale release andreturn s- The 515/164 valve may be actuated to release a bale manuallyby an operator on a tractor or automatically by a sensing 56] R fe Citedmeans which directly senses the diameter of a bale; and

UNITED STATES PATENTS is automatically returned from release position tobal- 3 680 296 8/1972 Beebout..... 56/16 4 mg position after a bale isreleased 3,110,145 11/1963 Avery 56 1 21 Claims, 5 Drawing Figures 9 r x\Z 24 28 26' 4/5 4;

47 4/ 1/ J2 J0 39 1/9 0 if 17 49 1 A N 'ZZ 1. 11: i 53 2:1 ff :1 I 1 1 2J6 35 Patented Aug. 14, 1973 3 Sheets-Sheet 1 ww NN WW mm Q I PatentedAug. 14, 1973 (5 Sheets-Sheet 5 GROUND ENGAGING HAY BALE ROLLINGAPPARATUS BACKGROUND OF THE INVENTION The only known prior art apparatusfor rolling a swath or a windrow of hay into bales in contact with theground is disclosed in Avery US. Pat. No. 3,110,145 and its counterpartAustralian and British patents. The Avery unit has driven baling chainmeans which is trained over one pair of fixed sprockets at the front,one pair of upper sprockets which are mounted on pivoted upper arms, andone pair of rear sprockets that are mounted on pivoted rear arms. Theupper arms are spring urged to an elevated position and swing downwardlyto permit the lower run ofthe baling chain to arch upwardly as the sizeof a bale increases. The rear arms are latched in a depending positionwhile a bale is rolled, and when the upper arms have moved down apredetermined distance they unlatch the rear arms which swing upwardlyand rearwardly to release a bale. Thereupon the rear arms drop bygravity to their original latched position and the spring means returnthe upper arms to their elevated position to start rolling another bale.During discharge the drive connection to the baling chain means isdisengaged.

The principle of the Avery baler is sound; but the drive and controlarrangements have some disadvantages.

SUMMARY OF THE INVENTION The principal object of the present inventionis to provide improved apparatus for rolling a swath or a window of hayinto a series of separate bales in contact with the ground. As usedherein, of course, the word hay is intended to include all fodder cropswhich are swathed or windrowed and are capable of being rolled into abale.

In accordance with the present invention, a hay bale rolling apparatusof the described type is entirely hydraulically powered and controlled.A hydraulic motor drives the baling chains, hydraulic cylinder andpiston means coupled with an accumulator controls movement of the upperarmsfrom a starting position to a terminal position and their return tothe starting position, and hydraulic power means serves both to nonnallyretain the rear arms in their depending position and also to elevatethose arms in order to release a finished bale from the balingapparatus.

A single, two-position, mechanical hydraulic control valve controls acycle of baling, bale release, and return to baling. In a runningposition of the valve the hydraulic motor operates to drive the balingchains, the hydraulic power means is conditioned to retain the rear armsin their depending position, and the hydraulic cylinder and piston meansis conditioned to extend gradually as the force created on the lower runof the chains by the increasing size of the bale exerts pressure toforce the upper arms downwardly. When a bale is to be released from theapparatus the mechanical control valve is moved to a release positionwhere the hydraulic motor is stopped, the hydraulic power means isoperated to elevate the rear arms and release a bale from the chamber,and the hydraulic cylinder and piston means, acting in concert with theaccumulator, returns the upper arms to their original positions as thepres sure on the lower run of chains is released.

LII

A mechanical linkage between the rear arms and the mechanical controlvalve acts when the arms have reached a predetermined elevated positionto return the valve to its running position which thus returns the reararms to their lowered position and again starts operation of thehydraulic motor. A check valve in the hydraulic motor circuit permitsthe motor to idle in reverse as the bale is released so that engagementbetween the chains and the finished bale does not inter fere with suchrelease.

Actuation of the mechanical control valve to move it from runningposition to release portion may be produced manually by an operator whois driving the tractor that tows the apparatus; or it may beautomatically produced by mechanical sensing means in the baling chamberincluding a pivoted arm which has a free end resting on top of a formingbale. When the arm reaches a predetermined position in accordance withthe desired size of bale to be produced, a mechanical connection betweenthe arm and themechanical control valve moves the valve from runningposition to release position.

As used herein the term "swath designates either a swath or a windrow.

DESCRIPTIONOF THE DRAWINGS FIG. 1 is a somewhat schematic sideelevational view of the apparatus of theinvention with the parts in theposition that they occupy during the early stages of the rolling of abale;

FIG. 2 is a plan view of the apparatus of FIG. 1 with parts omitted forclarity of illustration;

FIG. 3 is a generally schematic side elevational view which particularlyillustrates the mechanical actuating arrangements for the mechanicalcontrol valve;

FIG. 4 is a hydraulic diagram of the hydraulic system; and

FIG. 5 is a generally schematic perspective view to better illustratethe actuating means for the mechanical control valve.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings ingreater detail, and referring first to FIGS. 1 and 2, the apparatus ofthe present invention includes a frame, indicated generally at F, onwhich is mounted bale rolling means, indicated generally at R. Drive andcontrol of the bale rolling means R is produced by a mechanicallyactuated hydraulic system H which may be driven off the tractorshydraulic system or which may be powered by the tractor power take-off.

The frame F includes lower longitudinal side beams 10, upright forwardstructural members II, forwardly inclined rear structural members 12, asuper structure including the rearwardly inclined upper structuralmembers 13 and the horizontal top structural members 14, and a frontcross beam I5. Also part of the frame are diagonal side beams 16, adraft tongue 17 having a bifurcated forward end 170 for pivotalconnection to a tractor drawbar, and wheels I8 which are journalled onstub axles I8a at the sides of the lower beams 10. An enclosed platform19 at the front of the frame provides support for the controlcomponents, hydraulic motor and hydraulic accumulator of the hydraulicoperating and control system which will be described in more debers l3and 14 define the sides of a baling chamber B which is open at thebottom.

The bale rolling means R includes a drive shaft 21 which is journalledin the front lower portion of the frame F in the side plates 20, and apair of baling chain sprockets 22 are fixedly mounted upon the shaft 21spaced a substantial distance inwardly from the side plates as indicatedby the lines of the baler chains in FIG. 2. At the upper rear corners ofthe frame are fixed brackets 23 which support a fixed cross shaft 24 onwhich is journalled a pair of idler sprockets 25 that are in the samevertical planes with the sprockets 22.

A pair of upper, forward sprocket arms 26 are pivotally mounted at 27near their lower ends on the front diagonal super structure members 13and support a fixed cross shaft 28 upon which is journalled a pair offront upper sprockets 29 which are also in the same vertical planes withthe sprockets 22 and 25. The position of the forward sprocket arms 26 iscontrolled by parts of the hydraulic system H which will be describedhereinafter.

A pair of rear sprocket arms 30 are pivoted at 31 in the upper rearcorners of the frame, and at their free ends a fixed cross shaft 32provides support for a pair of rear, lower chain sprockets 33 that arealso in the same vertical planes with the sprockets 22, 25 and 29; andtrained around all of said sprockets is a pair of baling chains 34 whichare provided with cross raddles 35. The chains 34 have a lower chain run34a between the from lower sprockets 22 and the lower rear sprockets 33,and said lower runs engage hay lying upon the ground in a swath so as toroll the hay into a bale as the apparatus is drawn along by a tractor.As the bale increases in size the lower chain runs 34a arches higher andhigher within the baling chamber, and this is permitted by clockwisepivotal movement about the pivots 27 of the front sprocket support arms26.

The hydraulic system H includes a pair of hydraulic cylinders 36 each ofwhich is pivoted at 37 on a bracket 38, and each of which includes apiston rod 39 that is pivotally connected at 40 to a lower extension 260of one of the front sprocket support arms 26. Accordingly, swingingmovement of the arms 26 about their pivots 27 may be controlled by thehydraulic cylinder and piston units 36.

Hydraulic power means 41 in the form of a single rear cylinder andpiston unit is supported between a bracket 42 on the top structuralmember 14 and a forwardly extending bracket 43 on one of the pivotedarms 30, there being a pivotal connection 44 between the bracket 42 anda piston rod 45, and a pivotal connection 46 between the bracket 43 anda bifurcated support arm 47 on the end of the cylinder. Accordingly, thehydraulic control system H may act through the hydraulic power means 41either to retain the arms 30 in the position illustrated in FIG. 1 or topivot those arms upwardly and rearwardly about their pivots 31 byextending the piston rod 45.

The baling chains are driven by a hydraulic motor 48 having an outputshaft 49 on which a sprocket 50 is keyed, and a drive chain 51 istrained over the sprocket 50 and over a sprocket 52 on the chainsprocket shaft 21. A roller type chain tensioner 53 is adjustablymounted in the usual way.

Turning now to the hydraulic circuit of FIG. 4, the cylinder and pistonunits 36, the power unit 41, and the hydraulic motor 48 are allcontrolled by a hydraulic control circuit, indicated generally at 54,which includes a sump 55, a pump 56 which supplies fluid under pressureto the entire system, a mechanical control valve 57 which includes arelief valve 57a, a flow control valve 58 which controls the flow offluid to the motor 48, a check valve 59 in the circuit for the motor 48,an accumulator 60 which functions in cooperation with the cylinder andpiston units 36, a shut-off valve 61 and a pressure gauge 62.

A mechanical valve control, indicated generally at 63, includes apivoted control handle 64 which is balanced between a rear tensionspring 64 and a front tension spring 66 which are connected,respectively, to arms 67 and 68, both of which are fixedly mounted on arotatable transverse shaft 69.

In the position illustrated in FIGS. 3, 4 and 5, the control handle 64is toward the rear and the single mechanical control valve 57 is in arunning setting with hydraulic fluid supplied under pressure to thepower unit 41 to hold the rear sprocket arms in their downwardlyextending positions, and fluid is also supplied through the flow controlvalve 58 to the motor 48 which drives the bale rolling means R.Accordingly, as the bale rolling apparatus is drawn forwardly along aswath of hay by a tractor the bottom run 34a of the baling chains 34engages the hay in the windrow between the front lower sprocket 22 andthe rear lower sprocket 33 to roll it into a bale as the machine movesforwardly. The system including the cylinder and piston units 36 and theaccumulator 60 must be pregauged to a predetermined gauge pressure withthe arms 30 elevated, the shut off valve 61 is then closed and thesecomponents operate independently. The gauge pressure may be adjusted tovary the amount of pressure required to swing the arms 26 rearwardly andthus permit the lower chain run 34a to arch upwardly. This, then,determines how tightly the bale is rolled.

When a bale has reached a desired size for discharge, as determinedeither by the operator on the tractor or by sensing means in the balingchamber, indicated generally at 70, the control handle 64 may be movedforwardly against the tension of the spring 65 to shift the mechanicalcontrol valve 57 to a discharge position in which fluid under pressureis supplied to the power unit 41 to extend its piston rod 45, thusswinging the rear sprocket arms upwardly and rearwardly about theirpivots 31 to remove the cross shaft 32, the sprockets 33 and the chains34 from behind the rolled bale so that the machine may leave the bale inthe field. When the mechanical control valve 57 is in its releasesetting no fluid is supplied to the motor 48, and the check valve 59permits the motor to idle in reverse so that the bottom chain run 34acan move oppositely to the direction of the arrow in FIG. 1 in orderthat the bale engaging members 35 may not interfere with release of thebale.

The bale size sensing means 70 includes a transverse shaft 71 which ispivoted in the side plates 20 near the front of the baling chamber, andfixedly secured to the shaft 71 in the vertical longitudinal medianplane of the I baling chamber is a rearwardly extending sensing arm 72which has an idle position that is illustrated in full lines in FIG. 3where its free end rests upon a fonning bale. As the size of the baleincreases the sensing arm 72 moves toward the broken line position ofFIG. 3 and thus pivots the shaft 71 and an actuating arm 73, which isfixed on the shaft 71 outside the side frame, so that the actuating am73 turns counterclockwise as seen in FlGS. 3 and 5. A cable 74 connectsthe free end of the arm 73 with an actuating arm 75 which is fixed tothe outer end of the shaft 69 as seen in FIG. 5 so that thecounterclockwise movement of the arm 73 also produces counterclockwisemovement of the arm 75, the shaft 60 and the arm 68, thereby causing thetension spring to pull the valve operating arm 64 forwardly against thetension of the balancing spring 65. When the sensing arm 72 reaches apredetermined point in accordance with the size of the bale, theactuating arm 64 moves from its rearward running setting to its forwarddischarge setting. The point at which this takes place may be varied byadjusting the length of the cable 74.

In case the tractor operator wishes to manually control the time that abale is released, he may disconnect the cable 74 and move the controlarm 64 by means of a cable 76 which is attached to a manual actuatingarm 77 on the shaft 69.

Return of the valve control arm 64 from its release setting to itsrunning setting is automatic, through the operation of a return cable 78that is also attached to the arm 77 and to the bracket 43 on the rearsprocket support arm 30. When the support arm 30 reaches its fullyelevated position during bale release the cable 78 acts through the arm77 to turn the shaft 69 clockwise and thus release the tension on theforward spring 66 so that the rearward spring 65 may return theactuating arm 64 to its originalposition and thus return the controlvalve 57 to its running setting. The cable 78 may be adjusted to varythe exact position of the arms 30 at which the valve control arm 64 isreturned to running position. i

The foregoing detailed description is given for clearness ofunderstanding only and no unnecessary limitation should be understoodtherefrom, as modification will be obvious to those skilled in the art.

We claim:

1. Hay balerolling apparatus comprising, in combination:

a wheeled frame defining a baling chamber which is open at the bottom;bale rolling means movably supported in the baling chamber for engaginghay in a swath and rolling it into a bale in contact with the ground asthe apparatus moves along the swath, said bale rolling means including agenerally upright portion at the rear of the chamber which contacts therear of a bale to confine the bale as it is rolled; rotary hydraulicmotor means operatively connected to the bale rolling means to drive thelatter;

hydraulic power means for moving the generally upright bale confiningportion of the bale rolling means upwardly and rearwardly out of contactwith a bale to release said bale;

hydraulic control circuit means including a single mechanical controlvalve having a running setting in which the bale confining means is in abale rolling position and the hydraulic motor is driving the balerolling means, and a release setting for actuating the hydraulic powermeans to move the generally upright bale confining portion of the balerolling means to an elevated bale release position and for stopping themotor;

means for moving said mechanical control valve from its running settingto its release setting when a bale reaches a predetermined size;

and means for automatically returning said control valve to its runningsetting after release of a bale from the chamber.

2. The combination of claim 1 in which the means for moving themechanical control valve from its running setting to its release settingcomprises a manual actua tor accessible to an operator.

3. The apparatus of claim 1 in which the means for moving the mechanicalcontrol valve from its running setting to its release setting comprisessensing means in the baling chamber which directly senses the diameterof a bale, and means operatively connecting the sensing means to themechanical control valve to move said valve when a bale reaches apredetennined diameter.

4. The combination of claim 3 in which the sensing means comprises asensing arm in the baling chamber which is pivotally mounted on theframe on a generally horizontal axis and which has a free end resting ona bale as the latter is rolled, and in which the arm is mechanicallyconnected to the control valve.

5. The combination of claim 4 in which the mechanical connectionincludes means for adjusting the position of the sensing arm at whichthe valve is moved.

6. The combination of claim 4 in which the pivot axis for the sensingarm extends transversely near the front of the frame and the sensing armextends rearwardly generally in the longitudinal vertical median planeof the frame.

7. The combination of claim 1 in which the means for automaticallyreturning the control valve to its running setting comprises amechanical connection between the bale confining means and the controlvalve which returns the control valve when the confining means reachesits elevated position.

8. The combination of claim 1 in which the hydraulic control circuitmeans includes a check valve which permits the rotary hydraulic motor toidle in reverse when the control valve is in its release setting.

9. The combination of claim 1 in which the bale rolling means includesrotatable front sprocket means driven by the rotary hydraulic motor,rotatable rear sprocket means forming a part of the bale confiningmeans, rotatable upper sprocket means supported for bodily movement,chain means trained around all said sprocket means with a bale rollinglower chain run between the front and rear sprocket means, in whichhydraulic cylinder and piston means is operatively connected to theupper sprocket means to control movement of the latter between astarting position in which the lower chain run engages hay in a swathand a terminal position in which said lower chain run is arched over arolled bale in the chamber, and in which the hydraulic control circuitmeans includes an accumulator operatively associated with the cylinderand piston means so that said cylinder and piston means extends as thelower chain run arches progressively during the rolling of a bale andreturns when the bale is released.

10. Hay bale rolling apparatus comprising, in combination:

a wheeled frame defining a baling chamber which is open at the bottom;

rotatable front sprocket means and rotatable rear sprocket meanssupported by the frame within the bottom portion of the baling chamber,and rotatable upper sprocket means supported near the top of the frame;

upper support means mounting said upper sprocket means on the frame forbodily movement between a starting position and a terminal position;

hay rolling chain means trained around all said sprocket means with alower chain run between said front and rear sprocket means which engageshay in a swath on the ground;

means for driving one of the sprocket means so that the chain meansmoves forwardly in its lower run to roll hay into a bale in contact withthe ground as the apparatus moves along a swath, said lower run archingprogressively higher as the bale increases in size, and said archingbeing permitted by movement of the upper sprocket means toward terminalposition;

pivotal means on the frame for elevating the rear sprocket means;

sensing means in the baling chamber which contacts the circumferentialsurface of the bale to continuously sense the diameter of the bale;

actuating means for moving the pivotal means to release a bale from thechamber;

and means operatively connecting the sensing means to the actuatingmeans for initiating operation of the latter when the bale reaches apredetermined diameter.

ll. The combination of claim 10 in which the sensing means comprises asensing arm in the baling chamber which is pivotally mounted on theframe on a generally horizontal axis and which has a free end resting ona bale as the latter is rolled.

12. The combination of claim 11 in which the pivot axis for the sensingarm extends transversely near the front of the frame and the sensing armextends rearwardly generally in the longitudinal vertical median planeof the frame.

13. Hay bale rolling apparatus comprising, in combination:

a wheeled frame defining a baling chamber which is open at the bottom;

rotatable front sprocket means joumalled in the lower portion of theframe;

a pair of forward sprocket arms pivoted at their lower ends on the frameand having sprocket means journalled at their upper ends;

a pair of rear sprocket arms pivoted at their upper ends on the frameand having rear sprocket means journalled at their lower ends;

hay rolling chain means trained around all said sprocket means with alower chain run between said front and rear sprocket means which engageshay in a swath on the ground;

forward hydraulic cylinder and piston means on th frame controllingmovement of the forward sprocket arms between a starting position inwhich the lower chain run engages hay in a swath and a terminal positionin which the lower chain run is arched over a rolled bale in thechamber;

rearward hydraulic cylinder means on the frame operatively connected tothe rear sprocket arms to maintain said arms normally in a downwardlyextending position closing the rear of the baling chamber, said rearwardcylinder means being operable to elevate said arms and thereby open therear of the baling chamber;

hydraulic motor means for driving the front sprocket means;

hydraulic control circuit means including a single mechanical controlvalve having a running setting in which the rear hydraulic cylindermeans is retracted to retain the rear sprocket arms in their downwardlyextending positions and the hydraulic motor is driving the frontsprocket means, and a release setting for extending the rearwardhydraulic cylinder means and stopping the motor;

means for moving said mechanical control valve from its running settingto its release setting when a bale reaches a predetermined size;

and means for automatically returning said control valve to its runningsetting after release of a bale from the chamber.

14. The combination of claim 13 in which the means for moving themechanical control valve from its running setting to its release settingcomprises a manual actuator accessible to an operator on a tractor towhich the apparatus is attached.

15. The combination of claim 13 in which the means for moving themechanical control valve from its running setting to its release settingcomprises sensing means in the baling chamber which directly senses thediameter of a bale, and means operatively connecting the sensing meansto the mechanical control valve to move said valve when a bale reaches apredetermiend diameter.

16. The combination of claim 15 in which the sensing means comprises asensing arm in the baling chamber which is pivotally mounted on theframe on a generally horizontal axis and which has a free end resting ona bale as the latter is rolled, and in which the arm is mechanicallyconnected to the control valve.

17. The combination of claim 16 in which the mechanical connectionincludes means for adjusting the position of the sensing arm at whichthe valve is moved.

18. The combination of claim 13 in which the means for automaticallyreturning the control valve to its running setting comprises amechanical connection between the rear sprocket arms and the controlvalve which returns the control valve when said rear arms reach apredetermined elevated position.

19. The combination of claim 18 in which the mechanical connectionincludes means for adjusting the position of the rear arms at which thecontrol valve is returned.

20. The combination of claim 13 in which the hydraulic control circuitmeans includes a check valve which pennits the rotary hydraulic motor toidle in reverse when the control valve is in its release setting.

21. The combination of claim 13 in which the hydraulic control circuitmeans includes an accumulator operatively associated with the forwardhydraulic cylinder and piston means so that said cylinder and pistonmeans extends as the lower chain run arches progressively during therolling of a bale and returns when the bale is released.

a: x a: a: a:

1. Hay bale rolling apparatus comprising, in combination: a wheeled frame defining a baling chamber which is open at the bottom; bale rolling means movably supported in the baling chamber for engaging hay in a swath and rolling it into a bale in contact with the ground as the apparatus moves along the swath, said bale rolling means including a generally upright portion at the rear of the chamber which contacts the rear of a bale to confine the bale as it is rolled; rotary hydraulic motor means operatively connected to the bale rolling means to drive the latter; hydraulic power means for moving the generally upright bale confining portion of the bale rolling means upwardly and rearwardly out of contact with a bale to release said bale; hydraulic control circuit means including a single mechanical control valve having a running setting in which the bale confining means is in a bale rolling position and the hydraulic motor is driving the bale rolling means, and a release setting for actuating the hydraulic power means to move the generally upright bale confining portion of the bale rolling means to an elevated bale release position and for stopping the motor; means for moving said mechanical control valve from its running setting to its release setting when a bale reaches a predetermined size; and means for automatically returning said control valve to its running setting after release of a bale from the chamber.
 2. The combination of claim 1 in which the means for moving the mechanical control valve from its running setting to its release setting comprises a manual actuator accessible to an operator.
 3. The apparatus of claim 1 in which the means for moving the mechanical control valve from its running setting to its release setting comprises sensing means in the baling chamber which directly senses the diameter of a bale, and means operatively connecting the sensing means to the mechanical control valve to move said valve when a bale reaches a predetermined diameter.
 4. The combination of claim 3 in which the sensing means comprises a sensing arm in the baling chamber which is pivotally mounted on the frame on a generally horizontal axis and which has a free end resting on a bale as the latter is rolled, and in which the arm is mechanically connected to the control valve.
 5. The combination of claim 4 in which the mechanical connection includes means for adjusting the position of the sensing arm at which the valve is moved.
 6. The combination of claim 4 in which the pivot axis for the sensing arm extends transversely near the front of the frame and the sensing arm extends rearwardly generally in the longitudinal vertical median plane of the frame.
 7. The combination of claim 1 in which the means for automatically returning the control valve to its running setting comprises a mechanical connection between the bale confining means and the control valve which returns the control valve when the confining means reaches its elevated position.
 8. The combination of claim 1 in which the hydraulic control circuit means includes a check valve which permits the rotary hydraulic motor to idle in reverse when the control valve is in its release setting.
 9. The combination of claim 1 in which the bale rolling means includes rotatable front sprocket means driven by the rotary hydraulic motor, rotatable rear sprocket means forming a part of the bale confining means, rotatable upper sprocket means supported for bodily movement, chain means trained around all said sprockeT means with a bale rolling lower chain run between the front and rear sprocket means, in which hydraulic cylinder and piston means is operatively connected to the upper sprocket means to control movement of the latter between a starting position in which the lower chain run engages hay in a swath and a terminal position in which said lower chain run is arched over a rolled bale in the chamber, and in which the hydraulic control circuit means includes an accumulator operatively associated with the cylinder and piston means so that said cylinder and piston means extends as the lower chain run arches progressively during the rolling of a bale and returns when the bale is released.
 10. Hay bale rolling apparatus comprising, in combination: a wheeled frame defining a baling chamber which is open at the bottom; rotatable front sprocket means and rotatable rear sprocket means supported by the frame within the bottom portion of the baling chamber, and rotatable upper sprocket means supported near the top of the frame; upper support means mounting said upper sprocket means on the frame for bodily movement between a starting position and a terminal position; hay rolling chain means trained around all said sprocket means with a lower chain run between said front and rear sprocket means which engages hay in a swath on the ground; means for driving one of the sprocket means so that the chain means moves forwardly in its lower run to roll hay into a bale in contact with the ground as the apparatus moves along a swath, said lower run arching progressively higher as the bale increases in size, and said arching being permitted by movement of the upper sprocket means toward terminal position; pivotal means on the frame for elevating the rear sprocket means; sensing means in the baling chamber which contacts the circumferential surface of the bale to continuously sense the diameter of the bale; actuating means for moving the pivotal means to release a bale from the chamber; and means operatively connecting the sensing means to the actuating means for initiating operation of the latter when the bale reaches a predetermined diameter.
 11. The combination of claim 10 in which the sensing means comprises a sensing arm in the baling chamber which is pivotally mounted on the frame on a generally horizontal axis and which has a free end resting on a bale as the latter is rolled.
 12. The combination of claim 11 in which the pivot axis for the sensing arm extends transversely near the front of the frame and the sensing arm extends rearwardly generally in the longitudinal vertical median plane of the frame.
 13. Hay bale rolling apparatus comprising, in combination: a wheeled frame defining a baling chamber which is open at the bottom; rotatable front sprocket means journalled in the lower portion of the frame; a pair of forward sprocket arms pivoted at their lower ends on the frame and having sprocket means journalled at their upper ends; a pair of rear sprocket arms pivoted at their upper ends on the frame and having rear sprocket means journalled at their lower ends; hay rolling chain means trained around all said sprocket means with a lower chain run between said front and rear sprocket means which engages hay in a swath on the ground; forward hydraulic cylinder and piston means on the frame controlling movement of the forward sprocket arms between a starting position in which the lower chain run engages hay in a swath and a terminal position in which the lower chain run is arched over a rolled bale in the chamber; rearward hydraulic cylinder means on the frame operatively connected to the rear sprocket arms to maintain said arms normally in a downwardly extending position closing the rear of the baling chamber, said rearward cylinder means being operable to elevate said arms and thereby open the rear of the baling chamber; hydraulic motor means for driving the front sprocket means; hydraulic control circuit means including a single mechanical control valve having a running setting in which the rear hydraulic cylinder means is retracted to retain the rear sprocket arms in their downwardly extending positions and the hydraulic motor is driving the front sprocket means, and a release setting for extending the rearward hydraulic cylinder means and stopping the motor; means for moving said mechanical control valve from its running setting to its release setting when a bale reaches a predetermined size; and means for automatically returning said control valve to its running setting after release of a bale from the chamber.
 14. The combination of claim 13 in which the means for moving the mechanical control valve from its running setting to its release setting comprises a manual actuator accessible to an operator on a tractor to which the apparatus is attached.
 15. The combination of claim 13 in which the means for moving the mechanical control valve from its running setting to its release setting comprises sensing means in the baling chamber which directly senses the diameter of a bale, and means operatively connecting the sensing means to the mechanical control valve to move said valve when a bale reaches a predetermiend diameter.
 16. The combination of claim 15 in which the sensing means comprises a sensing arm in the baling chamber which is pivotally mounted on the frame on a generally horizontal axis and which has a free end resting on a bale as the latter is rolled, and in which the arm is mechanically connected to the control valve.
 17. The combination of claim 16 in which the mechanical connection includes means for adjusting the position of the sensing arm at which the valve is moved.
 18. The combination of claim 13 in which the means for automatically returning the control valve to its running setting comprises a mechanical connection between the rear sprocket arms and the control valve which returns the control valve when said rear arms reach a predetermined elevated position.
 19. The combination of claim 18 in which the mechanical connection includes means for adjusting the position of the rear arms at which the control valve is returned.
 20. The combination of claim 13 in which the hydraulic control circuit means includes a check valve which permits the rotary hydraulic motor to idle in reverse when the control valve is in its release setting.
 21. The combination of claim 13 in which the hydraulic control circuit means includes an accumulator operatively associated with the forward hydraulic cylinder and piston means so that said cylinder and piston means extends as the lower chain run arches progressively during the rolling of a bale and returns when the bale is released. 